Air conditioning performance requirements of larger vehicles, for example sport-utility vehicles or mini-vans, often means that in addition to the front (main) heating ventilating air conditioning (HVAC) unit, an auxiliary HVAC unit may be required to ensure adequate heating performance for the rear occupants. The auxiliary HVAC unit may result in a significant increase in components, vehicle weight, space, and cost.
An air conditioning apparatus with a single HVAC unit having two blowers, and providing conditioned air to the front and rear area of the vehicle cabin, is known by U.S. Patent Application Publication No. 2005/0126774. However, due to the configuration of its air conditioning case, the airflow amount provided to the front area of the vehicle cabin is affected by the airflow amount provided to the rear area of the vehicle cabin. Thus, the air conditioning apparatus disclosed by the U.S. Patent Application Publication No. 2005/0126774 cannot control front and rear airflow amounts separately with respect to the preferred front airflow level and the preferred rear airflow level, both of which can be set by a user of the vehicle.